Centro de Investigaciones en Química Biológica de Córdoba, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina.
DNA Repair (Amst). 2011 Nov 10;10(11):1106-13. doi: 10.1016/j.dnarep.2011.08.007. Epub 2011 Sep 1.
Human and Saccharomyces cerevisiae MutLα, and some bacterial MutL proteins, possess a metal ion-dependent endonuclease activity which is important for the in vivo function of these proteins. Conserved amino acids of the C-terminal region of human PMS2, S. cerevisiae PMS1 and of some bacterial MutL proteins have been implicated in the metal-binding/endonuclease activity. However, the contribution of individual amino acids to these activities has not yet been fully elucidated. In this work we show that Pseudomonas aeruginosa MutL protein possess an in vitro metal ion-dependent endonuclease activity. In agreement with previous published results, we observed that mutation of the aspartic acid, the first histidine or the first glutamic acid of the conserved C-terminal DMHAAHERITYE region results in nonfunctional in vivo proteins. We also determined that the arginine residue is essential for the in vivo function of this protein. However, we unexpectedly observed that although the first glutamic acid mutant derivative is not functional in vivo, its in vitro endonuclease activity is even higher than that of the wild-type protein.
人源和酿酒酵母 MutLα，以及一些细菌的 MutL 蛋白，均具有金属离子依赖性核酸内切酶活性，该活性对于这些蛋白的体内功能至关重要。人源 PMS2、酿酒酵母 PMS1 和一些细菌 MutL 蛋白的 C 末端保守区域的氨基酸，被认为与金属结合/核酸内切酶活性相关。然而，单个氨基酸对这些活性的贡献尚未完全阐明。在本工作中，我们证明铜绿假单胞菌 MutL 蛋白具有体外金属离子依赖性核酸内切酶活性。与先前发表的结果一致，我们观察到，保守的 C 末端 DMHAAHERITYE 区域中的天冬氨酸、第一个组氨酸或第一个谷氨酸的突变导致体内无功能的蛋白。我们还确定该蛋白的精氨酸残基对于其体内功能是必需的。然而，我们出人意料地观察到，尽管第一个谷氨酸突变体衍生物在体内没有功能，但它的体外核酸内切酶活性甚至高于野生型蛋白。
